It is now well recognised that there are inter-ethnic differences accounting for variations in both pharmacokinetics (PK) and pharmacodynamics (PD) of drugs, resulting in differences in drug responses. Treating physicians should be aware of pharmacogenetic differences that may exist between the races while extrapolating data generated from other populations to their own patients in order to ensure optimal treatment response and minimise toxicity. This is especially crucial in the practice of oncology where many anti-cancer drugs have narrow therapeutic indices. This paper discusses some commonly used drugs in cancer treatment where inter-ethnic differences in drug safety and efficacy are known to exist that are relevant to the Asian physician.
Inter-individual differences in drug responses are well recognised and may be due to genetic or environmental differences. These genetic or environmental influences may also result in inter-ethnic or inter-geographic differences in drug response. Indeed, drug regulatory authorities are beginning to acknowledge these differences. For example, in 1999, the United States Food and Drug Administration (FDA) recognised that drugs may be ethnically sensitive and advocated bridging studies for extrapolating clinical trial results from one region to another. At that time, they recommended collection of race and ethnicity information in clinical trials for the 3 main races: Caucasian, Black and Asian. In its updated document in 2005, the drug authority recognised the need to extend this race category further to include 5 minimum ethnic groups, namely, Caucasian, Black/African-American, Asian, American Indian/Alaska Native, and Native Hawaiian/other Pacific Islander.
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